Delirium and dementia are two of the most common causes of cognitive impairment in older populations, yet their interrelationship remains poorly understood. Previous studies have documented that dementia is the leading risk factor for delirium; and delirium is an independent risk factor for subsequent dementia. However, a major area of controversy is whether delirium is simply a marker of vulnerability to dementia, whether the impact of delirium is solely related to its precipitating factors, or whether delirium itself can cause permanent neuronal damage and lead to dementia. Ultimately, it is likely that all of these hypotheses are true. Emerging evidence from epidemiological, clinicopathological, neuroimaging, biomarker, and experimental studies provide support for a strong interrelationship and for both shared and distinct pathological mechanisms. Targeting delirium for new preventive and therapeutic approaches may offer the sought-after opportunity for early intervention, preservation of cognitive reserve, and prevention of irreversible cognitive decline in ageing.

Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Postoperative delirium and postoperative cognitive dysfunction share risk factors and may co-occur, but their relationship is not well established. The primary goals of this study were to describe the prevalence of postoperative cognitive dysfunction and to investigate its association with in-hospital delirium. The authors hypothesized that delirium would be a significant risk factor for postoperative cognitive dysfunction during follow-up. Methods This study used data from an observational study of cognitive outcomes after major noncardiac surgery, the Successful Aging after Elective Surgery study. Postoperative delirium was evaluated each hospital day with confusion assessment method–based interviews supplemented by chart reviews. Postoperative cognitive dysfunction was determined using methods adapted from the International Study of Postoperative Cognitive Dysfunction. Associations between delirium and postoperative cognitive dysfunction were examined at 1, 2, and 6 months. Results One hundred thirty-four of 560 participants (24%) developed delirium during hospitalization. Slightly fewer than half (47%, 256 of 548) met the International Study of Postoperative Cognitive Dysfunction-defined threshold for postoperative cognitive dysfunction at 1 month, but this proportion decreased at 2 months (23%, 123 of 536) and 6 months (16%, 85 of 528). At each follow-up, the level of agreement between delirium and postoperative cognitive dysfunction was poor (kappa less than .08) and correlations were small (r less than .16). The relative risk of postoperative cognitive dysfunction was significantly elevated for patients with a history of postoperative delirium at 1 month (relative risk = 1.34; 95% CI, 1.07–1.67), but not 2 months (relative risk = 1.08; 95% CI, 0.72–1.64), or 6 months (relative risk = 1.21; 95% CI, 0.71–2.09). Conclusions Delirium significantly increased the risk of postoperative cognitive dysfunction in the first postoperative month; this relationship did not hold in longer-term follow-up. At each evaluation, postoperative cognitive dysfunction was more common among patients without delirium. Postoperative delirium and postoperative cognitive dysfunction may be distinct manifestations of perioperative neurocognitive deficits.

Background and Objectives: While there are qualitative studies examining the delirium-related experiences of patients, family caregivers, and nurses separately, little is known about common aspects of delirium burden among all three groups. We describe common delirium burdens from the perspectives of patients, family caregivers, and nurses. Research Design and Methods: We conducted semistructured qualitative interviews about delirium burden with 18 patients who had recently experienced a delirium episode, with 16 family caregivers, and with 15 nurses who routinely cared for patients with delirium. We recruited participants from a large, urban teaching hospital in Boston, Massachusetts. Interviews were recorded and transcribed. We used interpretive description as the approach to data analysis. Results: We identified three common burden themes of the delirium experience: Symptom Burden (Disorientation,

Importance: Measurement of delirium severity has been recognized as highly important for tracking prognosis, monitoring response to treatment, and estimating burden of care both during and after hospitalization. Rather than simply rating delirium as present or absent, the ability to quantify its severity will enable development and monitoring of more effective treatment approaches for delirium. Objective: This study had 3 major goals: to present a comprehensive review of delirium severity instruments; to conduct a methodologic quality rating of the original validation study of the most commonly used instruments; and to select a group of top-rated instruments. Evidence Review: Using key words, subject headings, and full text approaches, we conducted a systematic review of the following databases,

Background: Delirium has been associated with more rapid cognitive decline. However, it is 39 unknown whether increased delirium severity is associated with a higher rate of long-term 40 cognitive decline. 41Objective: To evaluate delirium severity and the presence and rate of cognitive decline over 36 42 months following surgery. Conclusion: Patients with the highest delirium severity experienced the greatest rate of cognitive 59 decline, which exceeds the rate previously observed for patients with dementia, on serial 60 3 neuropsychological testing administered over 3 years, with a dose-response relationship 61 between delirium severity and long-term cognitive decline. 62